The present invention relates generally to integrated circuit (IC) manufacturing and more particularly, to methods and systems for separating a semiconductor wafer into multiple ICs.
Integrated circuits (ICs) are typically manufactured in the form of multiple ICs on a single semiconductor wafer. By way of example, a single semiconductor wafer can include hundreds or even thousands of individual ICs. Once the ICs are created on the semiconductor wafer, the wafer is inspected for manufacturing defects. This inspection typically identifies portions of the semiconductor wafer and the ICs contained therein that may not function properly due to detected manufacturing defects. The semiconductor wafer is then cut (i.e., diced) to separate the ICs. Each IC is then typically picked-up and placed in a package for subsequent interconnection to other electrical and physical components.
The package provides electrical contacts, physical and often thermal support for the IC. The package electrical contacts include internal contacts that provide an electrical connection between the package and the contacts (pads, bumps, etc.) on the IC. The package also includes external contacts that provide an electrical connection between the package and any external electrical circuits and components. The corresponding internal contacts and the external contacts are electrically connected. The external contacts are typically larger and more separated than the contacts pads or bumps on the IC itself. The larger, external contacts make it easier to connect external electrical circuits and components to the IC.
Typically, each IC is placed in their respective package by a machine such as a robot in what is commonly referred to as a pick and place operation. The robot picks-up each IC individually and places the IC precisely into the corresponding package. The pick and place robot is typically a very expensive machine so that the robot can move quickly and accurately. The pick and place robot also has a limited throughput because only one or possibly two robots can pickup the ICs. This limited throughput is not a problem for most applications, however, as the number of individual ICs on each semiconductor wafer is increased, the robot's throughput limitation can become problematic.
By way of example, a typical pick and place operation requires about 1 second for the robot to pickup and place each IC. If the semiconductor wafer includes 200 microprocessor ICs then about 200 seconds (3.33 minutes) are required to pickup and place all of the microprocessor ICs. Conversely, if the semiconductor wafer includes 7500 radio frequency identification (RFID) ICs, then the typical pick and place robot would require about 7500 seconds (about 2 hours and 5 minutes) to pickup and place each RFID IC.
One approach to pick and placing many smaller ICs is referred to as a fluidic self assembly (FSA) operation. The FSA operation includes flowing a slurry containing numerous ICs over a surface of a substrate. The substrate has multiple recessed regions. Each recessed rejoin is shaped (e.g., beveled) in such a way that the IC can only fit in a desired orientation.
FSA provides significant improvements in the throughput but with significant shortfalls. The typical FSA operation has relatively low yields of about 60% operationally placed ICs. One reason the ICs fail to be operationally placed is because the nonconforming ICs are added to the slurry and therefore placed in the substrate. If the ICs are sorted prior to being added to the slurry, the pick and place limitations above apply and there is no significant throughput advantage of the FSA process.
Further, the FSA operation does not provide a very efficient package operation. After the FSA operation, each IC is typically soldered to the substrate and a lager portion of the ICs can fail (poor and/or shorted connections) in the soldering operation. Further still, the FSA does not provide effective physical support for the ICs during the remaining packaging operations and many ICs crack and otherwise fail for mechanical reasons.
Therefore, neither the typical pick and place robot operation nor the typical FSA operations are fast enough for placing and packaging ICs. In view of the foregoing, there is a need for a faster, more efficient and more economical system and method for separating and packaging ICs.